Search

Free-standing electrode (FSE) architectures hold the potential to dramatically increase the gravimetric and volumetric energy density of lithium-ion batteries (LIBs) by eliminating the parasitic dead weight and volume associated with traditional metal foil current collectors. However, current FSE fabrication methods suffer from insufficient mechanical stability, electrochemical performance, or industrial adoptability. Here, we demonstrate a scalable camphene-assisted fabrication method that allows simultaneous casting and templating of FSEs comprising common LIB materials with a performance superior to their foil-cast counterparts. These porous, lightweight, and robust electrodes simultaneously enable enhanced rate performance by improving the mass and ion transport within the percolating conductive carbon pore network and eliminating current collectors for efficient and stable Li

The highly reactive nature and rough surface of Li foil can lead to the uncontrollable formation of Li dendrites when employed as an anode in a lithium metal battery. Thus, it could be of great practical utility to create uniform, electrochemically stable, and "lithiophilic" surfaces to realize homogeneous deposition of Li. Herein, a LiZn alloy layer is deposited on the surface of Li foil by e-beam evaporation. The idea is to introduce a uniform alloy surface to increase the active area and make use of the Zn sites to induce homogeneous nucleation of Li. The results show that the alloy film protected the Li metal anode, allowing for a longer cycling life with a lower deposition overpotential over a pure-Li metal anode in symmetric Li cells. Furthermore, full cells pairing the modified lithium anode with a LiFePO4 cathode showed an incremental increase in Coulombic efficiency compared with pure-Li. The concept of using only an alloy modifying layer by an in-situ e-beam deposition synthesis method offers a potential method for enabling lithium metal anodes for next-generation lithium batteries.

Electrochemical water splitting is one of the most promising approaches for sustainable energy conversion and storage toward a future hydrogen society. This demands durable and affordable electrocatalysts for the hydrogen evolution reaction (HER) and the oxygen evolution reaction (OER). In this study, we report the preparation of uniform Ni–P–O, Ni–S–O, and Ni–S–P–O electrocatalytic films on nickel foam (NF) substrates via flow cell-assisted electrodeposition. Remarkably, electrodeposition onto 12 cm2 substrates was optimized by strategically varying critical parameters. The high quality and reproducibility of the materials is attributed to the use of a 3D-printed flow cell with a tailored design. Then, the as-fabricated electrodes were tested for overall water splitting in the same flow cell under alkaline conditions. The best-performing sample, NiSP/NF, required relatively low overpotentials of 93 mV for the HER and 259 mV for the OER to produce a current density of 10 mA cm−2. Importantly, the electrodeposited films underwent oxidation into amorphous nickel (oxy)hydroxides and oxidized S and P species, improving both HER and OER performance. The superior electrocatalytic performance of the Ni–S–P–O films originates from the unique reconstruction process during the HER/OER. Furthermore, the overall water splitting test using the NiSP/NF couple required a low cell voltage of only 1.85 V to deliver a current density of 100 mA cm−2. Overall, we demonstrate that high-quality electrocatalysts can be obtained using a simple and reproducible electrodeposition method in a robust 3D-printed flow cell.

Nickel adds to the capacity of layered oxide cathodes of lithium-ion batteries but comprises their stability. We report a petal-grained Li[Ni0.89Co0.10Sb0.01]O2 cathode that is, nevertheless, stable. The stability originates from the ordering of the nanosized grains in a dense, flower-petal-like array, where the elongated and nearly parallel grains radiate from the center to the surface. The ordering of the grains prevents microcrack generation from abrupt lattice changes of the stressful H2-H3 phase transition. The tight packing of the nanograins is conserved upon cycling, preventing destructive seepage of the electrolytic solution into the particles. The half-cell, cycling between 2.7-4.3 V versus Li/Li+ at a 0.5 C rate retains 95.0% of its initial capacity of 220 mAh g-1 after 100 cycles. The full-cell, cycling with a graphite anode and between 3.0-4.2 V at a 1 C rate, retains 83.9% of its initial capacity after 1000 cycles.

The low cost, abundance, and high capacity of sodium and sulfur make them attractive battery materials. However, formation and migration of polysulfides in sulfur batteries causes rapid capacity fade, limiting battery cycle life. Most strategies to mitigate polysulfide shuttling address migration rather than formation and require complicated or expensive synthetic steps. Here, we introduce an amorphous, sulfur-rich molybdenum sulfide as a sulfur equivalent cathode that is simple and easy to make and shows excellent cycling performance with a specific capacity of 537 mAh g–1 at 50 mA g–1, retaining over 200 mAh g–1 at a rate of 1 A g–1.

Selenium-doped germanium (GeSe) micrometer-sized particles have been reported with good cycling performance and rate capability due to a Li–Se–Ge network formed during the first lithiation that pro...

This Perspective discusses the prospective strategies for overcoming the stability and capacity trade-off associated with increased Ni content in layered Ni-rich Li[NixCoyMnz]O2 (NCM) and Li[NixCoy...

Porphyrins play pivotal roles in many crucial biological processes including photosynthesis. However, there is still a knowledge gap in understanding electronic and excited state implications associated with functionalization of the porphyrin ring system. These effects can have electrochemical and spectroscopic signatures that reveal the complex nature of these somewhat minor substitutions, beyond simple inductive or electronic effect correlations. To obtain a deeper insight into the influences of porphyrin functionalization, four free-base, meso-substituted porphyrins: tetraphenyl porphyrin (TPP), tetra(4-hydroxyphenyl) porphyrin (THPP), tetra(4-carboxyphenyl) porphyrin (TCPP), and tetra(4-nitrophenyl) porphyrin (TNPP), were synthesized, characterized, and investigated. The influence of various substituents, (-hydroxy,-carboxy, and -nitro) in the para position of the meso-substituted phenyl moieties were evaluated by spectroelectrochemical techniques (absorption and fluorescence), femtosecond transient absorption spectroscopy, cyclic and differential pulse voltammetry, ultraviolet photoelectron spectroscopy (UPS), and time-dependent density functional theory (TD-DFT). Spectral features were evaluated for the neutral porphyrins and differences observed among the various porphyrins were further explained using rendered frontier molecular orbitals pertaining to the relevant transitions. Electrochemically generated anionic and cationic porphyrin species indicate similar absorbance spectroscopic signatures attributed to a red-shift in the Soret band. Emissive behavior reveals the emergence of one new fluorescence decay pathway for the ionic porphyrin, distinct from the neutral macrocycle. Femtosecond transient absorption spectroscopy analysis provided further analysis of the implications on the excited-state as a function of the para substituent of the free-base meso-substituted tetraphenyl porphyrins. Herein, we provide an in-depth and comprehensive analysis of the electronic and excited state effects associated with systematically varying the induced dipole at the methine bridge of the free-base porphyrin macrocycle and the spectroscopic signatures related to the neutral, anionic, and cationic species of these porphyrins.

To understand the effect of selenium doping on the good cycling performance and rate capability of a Ge0.9Se0.1 electrode, the dynamic morphological and phase changes of the Ge0.9Se0.1 electrode were investigated by synchrotron-based operando transmission X-ray microscopy (TXM) imaging, X-ray diffraction (XRD), and X-ray absorption spectroscopy (XAS). The TXM results show that the Ge0.9Se0.1 particle retains its original shape after a large volume change induced by (de)lithiation and undergoes a more sudden morphological and optical density change than pure Ge. The difference between Ge0.9Se0.1 and Ge is attributed to a super-ionically conductive Li–Se–Ge network formed inside Ge0.9Se0.1 particles, which contributes to fast Li-ion pathways into the particle and nano-structuring of Ge as well as buffering the volume change of Ge. The XRD and XAS results confirm the formation of a Li–Se–Ge network and reveal that the Li–Se–Ge phase forms during the early stages of lithiation and is an inactive phase. The Li–Se–Ge network also can suppress the formation of the crystalline Li15Ge4 phase. These in situ and operando results reveal the effect of the in situ formed, super-ionically conductive, and inactive network on the cycling performance of Li-ion batteries and shed light on the design of high capacity electrode materials.

A tin oxide-carbon composite (SnOx-C) was fabricated as a candidate for use as an anode in lithium-ion batteries through the pyrolysis of a ditin citrate precursor. The simultaneous formation of ti...

There is a need to develop high-capacity, stable anode materials for the next generation of lithium ion batteries that will power consumer electronics and automobiles of the future. This report des...

Layered nickel-rich cathode particles for lithium-ion batteries can fail and severely limit the cycling performance via cracking from anisotropic strain which allows electrolyte penetration and the...

The dynamic information of lithium-ion battery active materials obtained from coin cell-based in-situ characterizations might not represent the properties of the active material itself because many other factors in the cell could have impacts on the cell performance. To address this problem, a single particle cell was developed to perform the in-situ characterization without the interference of inactive materials in the battery electrode as well as the X-ray-induced damage. In this study, the dynamic morphological and phase changes of selenium-doped germanium (Ge0.9 Se0.1 ) at the single particle level were investigated via synchrotron-based in-situ transmission X-ray microscopy. The results demonstrate the good reversibility of Ge0.9 Se0.1 at high cycling rate that helps understand its good cycling performance and rate capability. This in-situ and operando technique based on a single particle battery cell provides an approach to understanding the dynamic electrochemical processes of battery materials during charging and discharging at the particle level.

The performance of the rechargeable Li metal battery anode is limited by the poor ionic conductivity and poor mechanical properties of its solid-electrolyte interphase (SEI) layer. To overcome this, a 3 : 1 v/v ethyl methyl carbonate (EMC) : fluoroethylene carbonate (FEC) containing 0.8 M lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) and 0.2 M lithium difluoro(oxalate)borate (LiDFOB) dual-salts with 0.05 M lithium hexafluorophosphate (LiPF6) was tested to promote the formation of a multitude of SEI-beneficial species. The resulting SEI layer was rich in LiF, Li2CO3, oligomeric and glass borates, Li3N, and Li2S, which enhanced its role as a protective yet Li+ conductive film, stabilizing the lithium metal anode and minimizing dead lithium build-up. With a stable SEI, a Li/Li[Ni0.59Co0.2Mn0.2Al0.01]O2 Li-metal battery (LMB) retains 75% of its 177 mA h g−1 specific discharge capacity for 500 hours at a coulombic efficiency of greater than 99.3% at the fast charge–discharge rate of 1.8 mA cm−2.

We report the fabrication and electrochemical performance of metal-foil free Li4Ti5O12 (LTO) and LiNi1/3Co1/3Mn1/3O2 (NCM) electrodes supported on conductive and porous reduced graphene oxide/poly(acrylic acid) (rGO-PAA) aerogels. The highly porous rGO-PAA (∼6 mg cm–3) enables slurry infiltration of LTO and NCM to form composite electrodes with tunable mass loadings (∼3–30 mg cm–2), and the resultant composites can withstand 100-fold compression (from 3.2 mm to ∼30–130 μm) to achieve electrode densities of 2–3 g cm–3. The adequate compressibility of the rGO-PAA coupled with removal of the conventional metal-foil weight and volume provides high volumetric energy densities of 1723 Wh L–1 for NCM and 625 Wh L–1 for LTO at low power density, representing a 25% increase in energy density over similar electrodes built with metal-foil current collectors. These metrics demonstrate the utility of the rGO-PAA current collector to reduce the weight and volume of lithium-ion electrodes without sacrificing energy density.

Irreversible capacity loss is a critical problem in high capacity anode materials of Li-ion batteries, such as silicon, germanium, and tin. In addition to solid electrolyte interface formation and active material loss, Li trapping in high capacity anode materials during cycling has been considered a new mechanism of capacity loss but received less attention. In this study, we used single particle battery-based in situ focused ion beam-scanning electron microscopy, transmission electron microscopy (TEM), and scanning TEM to investigate the microstructure and composition of germanium nanopores formed at the end of delithiation. Our results show that a significant amount of Li accumulates inside the nanopores.

In this work we demonstrate how hydrogen can be utilized to fine tune the emission gap of C60 through the formation of direct C H bonds in sodium and lithium intercalated systems (M6C60Hx). Upon hydrogenation, a shift in the emission spectrum to shorter wavelengths (higher energy) is observed relative to alkali metal free fulleranes (C60Hx) and pure C60. This is attributed to the higher degree of hydrogenation of C60 that can be achieved upon intercalation with alkali metals which increases the sp3 hybridization of the system (decreases conjugation). Quantum yields of the sodium and lithium intercalated fulleranes are 1.3% and 1.8% respectively which are similar to those of alkali metal free fulleranes (1.4%). We also show that polymethyl methacrylate (PMMA) can be infused with the metal intercalated fulleranes to produce a fluorescent polymer with excellent transparency over the visible spectrum. This could potentially lead to further use of these materials in luminescent down shifting applications.

We describe here the metal-templated transformation of carbon nitride (C3N4) into nitrogen-containing carbons as anodes for Li-ion batteries (LIBs). Changing the template from the carbon- and nitrogen-immiscible Cu powder to the carbon- and nitrogen-miscible Fe powder yields different carbons; while Fe templating produces graphitized carbons of low (

This study aims to provide a new platform for the fabrication of metal-carbon composites. Herein we show that the high density crosslinking of a polymer can be used to homogenously trap metal nanoparticles and other components. In this setting, we utilized the cross-linking of poly(maleic anhydride-at 1-octadecene) [PMAO] with ethylene glycol to trap metal nanoparticles and carbon nitride (C3N4) within the polymeric structure. During inert, high-temperature pyrolysis, the polymer acts as a soft-template and prevents agglomeration of metallic tin during the synthesis. Inspired by the work of Tang et al. the carbon nitride is employed to act as a nitrogen dopant source and textural template for the final product. Through an analysis variable experimental parameter, we have shown that this method provides an avenue for the tunable fabrication of nitrogen-rich porous composites. To demonstrate the practicality of this synthetic method, composites with a variety of different nitrogen moieties and textural compositions were electrochemically analyzed. The resulting composites were then used as a platform to demonstrate not only the tunability of the synthetic method but also an example of how much these effects drastically dictate the electrochemistry of the system. Of the samples analyzed it was shown that a urea based composite demonstrated the best electrochemistry touting high rate capability, stable cycling, and high coulombic efficiency (CE). The results of long-term performance testing reveal the excellent electrochemical properties of the U-Sn-CN composite, supplying an initial capacity of ~ 600 mAh g–1 and 82.0 % capacity retention over 400 cycles at a high current density of 1 A g–1 (1C) with an average CE of 99.8 %. Lower current density studies [500 mA g-1 (C/2)] have shown the material to have an initial capacity of ~ 640 mAh g–1 with 86.0 % capacity retention over 400 cycles. Electrochemical and post-mortem analysis of this composite material suggest the performance properties can be attributed to the unique nitrogen-doped carbon framework, which is able to buffer the large volumetric expansion of the tin due to its disordered flexible nature whilst contributing to the overall capacity of the composite from its high degree of nitrogen doping (~11.9 at %). Figure 1

In layered oxide cathodes for lithium-ion batteries, nickel provides high capacity but compromises stability. Although much progress has been made in upsetting this trade-off, the stability of Ni-rich cathodes is not yet adequate to satisfy the expectations of commercial batteries. Here, a layered Li[Ni0.89Co0.10Sb0.01]O2 cathode material, which overcomes the instabilities associated with highly Ni-rich cathodes to deliver excellent capacity retention, is reported. This cathode shows a significantly enhanced resistance to performance deterioration and microcrack propagation compared to the more conventional Li[Ni0.885Co0.10Al0.015]O2 material. Furthermore, it delivers more capacity than its counterpart despite the same nickel content. The robustness of the material arises from the ordering of the grains into a dense flower-petal arrangement, which collectively preserves the coherency of the particle. Through extensive cross-sectional imaging and chemical mapping, a correlation between microcracks and electrolyte infiltration into the particle is demonstrated. Figure 1

Germanium (Ge) is a promising candidate for high-capacity Li-ion battery anode due to its high theoretical capacity of 1384 mAh/g (for the charged Li15Ge4 phase), low operation voltage, fast bulk Li diffusion, and high electrical conductivity. However, the major challenge in the development of Ge anode is the large volume change involved in the reaction scheme, which could result in rapid loss of specific capacity. We recently reported that selenium (Se) -doped Ge (GeSe) forms an inactive phase that buffers the volumetric expansion of Ge which provides better cycling life and performance (1). However, the dynamic morphological and chemical transformations of GeSe that occur during battery cycling processes is still elusive. The traditional in-situ coin cell has rotating limitations which makes three-dimensional experiment difficult except via limited angle tomography. It also suffers from X-ray damage problems to the binder. To understand the dynamic morphological and chemical changes of GeSe, we developed a single particle battery cell for operando TXM and XANES. A micron-sized GeSe particle was attached to a pre-coated tungsten probe by ion beam carbon deposition on a Zeiss Nvision 40 FIB-SEM at the Center for Nanoscale Materials, Argonne National Laboratory. The single particle battery cell was assembled in an argon-filled glovebox. A small piece of Li metal was attached to a copper wire as the counter electrode. Both the tungsten and lithium electrodes were carefully inserted into a funnel-shaped open-ended silica capillary and stabilized via epoxy. The quartz housing was fully filled with 1 M LiPF6 EC/DEC electrolyte through a micro-syringe and sealed with torr seal epoxy. This binder free operando single particle cell eliminates discrepancies caused by particles overlapping in the in-situ coin cell during TXM and the impact of X-ray damage to the binder (2). It provides chemical and morphological information in three-dimensional space via computed nanotomography coupled with XANES. Figure 1 shows the performance of operando GeSe cell and the 2D morphological change of a GeSe particle attached to the tungsten probe at 11.113 keV. Regardless of the defect caused by the carbon deposition process, the results indicate that GeSe undergoes a different dynamic chemical transformation compared to pure Ge. The selenium-doped germanium has the ability to reinstate its original shape after cycling. This study can help to understand the mechanical stability and degradation mechanism of high capacity lithium alloy anode with additional stress-accommodating phase. K. C. Klavetter, J. Pedro de Souza, A. Heller, C. B. Mullins, High tap density microparticles of selenium-doped germanium as a high efficiency, stable cycling lithium-ion battery anode material. Journal of Materials Chemistry A 3, 5829-5834 (2015). L. Y. Lim, N. Liu, Y. Cui, M. F. Toney, Understanding Phase Transformation in Crystalline Ge Anodes for Li-Ion Batteries. Chemistry of Materials 26, 3739-3746 (2014). Figure 1

Increasingly modern society relies on the use of electrical energy for a large portion of their everyday tasks. Many of these tasks require the use of portable energy sources. Currently, lithium ion batteries (LIBsdominate the portable energy storage market.1 Almost exclusively, these LIBs utilize a graphite anode, due to graphite’s long lifetime and high capacity retention.2 This project aims to develop a cheap, high capacity alternative to graphite via a SnO2-C based anode material. Tin oxide is an effective candidate for an anode due to its low price and tin’s high abundance. Tin oxide anodes have been studied previously, motivated by its high theoretical capacity (1494 mAh/g).2 However, tin oxide is not currently used in commercial cells because of the large volumetric expansion during lithiation (up to 300%) leading to fracturing of the particle.3 In turn, the fracturing can cause the particle to electrically disconnect from the current collector and lose effectiveness. We believe these issues can be counteracted through the employment of a carbon backbone. The presence of semi-crystalline carbon could act as a flexible component to resist the expansion of the tin atoms, preventing the degradation and fracturing of the particle caused by expansion.4 Previous studies have utilized SnO2-C composites to form anodic materials with high capacities and high columbic efficiencies, but tend to display sub-par cycling lifetimes.4,5 However, these studies did not examine how the effects of doping and extent of crystallinity can influence the overall electrochemical performance. The analysis of these factors could lead to the production of a higher capacity and more economically viable alternative to graphitic anodes. The goal of this research is to develop SnO2-C anodes and investigate the storage and transport of Li within the electrodes to improve the efficiency and cost of LIBs. Due to their higher tap densities and industrial viability, micron-sized anode materials were generated for this study. Ditin citrate was chosen as a tin containing pyrolysis precursor because of its novelty and inexpensive synthesis.6 Precursors such as sucrose and citric acid were added to pyrolysis mixture to form a semi-graphitized framework around the tin-oxide particles. XRD, Raman, XPS, and SEM/EDX data suggest the uniform coating of a semi-graphitized coating around the SnO2 particles. Preliminary data suggest this process has led to the formation of a high specific capacity (750 mA/g) anode material with satisfactory cycling performance. The future pursuits of this study is to optimize the cycling performance and determine the effects of using dopants such as nitrogen and sulfur. 1. Tenan, M. S.; LaFiandra, M. E.; Ortega, S. V. The Effect of Soldier Marching, Rucksack Load, and Heart Rate on Marksmanship. Hum. Factors 2017, 59 (2), 259–267. https://doi.org/10.1177/0018720816671604 2. Thampan, T.; Shah, D.; Cook, C.; Novoa, J.; Shah, S. Development and Evaluation of Portable and Wearable Fuel Cells for Soldier Use. J. Power Sources 2014, 259, 276–281. https://doi.org/10.1016/j.jpowsour.2014.02.099 3. Zhu, X.; Zhu, Y.; Murali, S.; Stoller, M. D.; Ruoff, R. S. Reduced Graphene Oxide/Tin Oxide Composite as an Enhanced Anode Material for Lithium Ion Batteries Prepared by Homogenous Coprecipitation. J. Power Sources 2011, 196 (15), 6473–6477. https://www.sciencedirect.com/science/article/pii/S0378775311008020 4. Winter, M.; Besenhard, J. O. Electrochemical Lithiation of Tin and Tin-Based Intermetallics and Composites. Electrochim. Acta 1999, 45 (1), 31–50. https://www.sciencedirect.com/science/article/pii/S0013468699001917 5. Paek, S.-M.; Yoo, E.; Honma, I. Enhanced Cyclic Performance and Lithium Storage Capacity of SnO2/Graphene Nanoporous Electrodes with Three-Dimensionally Delaminated Flexible Structure. Nano Lett. 2009, 9 (1), 72–75. https://pubs.acs.org/doi/10.1021/nl802484w 6. Derrien, G.; Hassoun, J.; Panero, S.; Scrosati, B. Nanostructured Sn–C Composite as an Advanced Anode Material in High-Performance Lithium-Ion Batteries. Adv. Mater. 2007,19 (17), 2336–2340. https://onlinelibrary.wiley.com/doi/abs/10.1002/adma.200700748 Figure 1

We report here the synthesis and fabrication of reduced graphene oxide (rGO)-based aerogels as free-standing lithium-ion battery (LIB) electrodes and 3D scaffolds for supporting conventional LIB active materials (e.g., LiFePO4, Li4Ti5O12, LiNixCoyMnzO2). As a 3D replacement for conventional metal-foil current collectors, we demonstrate the fabrication of compact (2 – 3 g cm-3) electrodes via slurry-infiltrating the porous aerogels with controlled active-material loading (~3 – 30 mg cm-2) and compressing the resultant composites to a desired thickness (~30 – 130 μm from a starting thickness of 3.2 mm). The controlled loading and tunable thickness provide high composite electrode densities that are of essence for consideration in a practical application. Replacement of the usual copper foil (anode) and aluminum foil (cathode) current collectors with the lightweight, integrated rGO-based aerogels drastically reduces the weight and volume occupied by the current collector, thereby increasing the energy density per unit volume and mass at the electrode level. We further demonstrate that the addition of poly (acrylic acid) (PAA) to the rGO scaffold (referred to as rGO-PAA) provides a versatile platform for exploring a diverse range of structure-function relationships that will guide our understanding of fabricating high-performance electrodes with the lightweight rGO aerogels. For example, due to the electrically-insulating nature of PAA, reducing its content is expected to lead to an increase in electrical conductivity of the aerogel; conversely, we show that the incorporation of PAA facilitates a more uniform pore structure that is expected to improve the ionic conductivity of Li+ ions in the electrolyte. We are exploring this versatility to identify requisite synthesis and processing conditions that optimize the trade-off between electrical conductivity, pore structure, and mechanical properties in the rGO-based aerogels. Overall, the straightforward synthesis of the rGO-based aerogels starting from inexpensive precursors (graphite and poly (acrylic acid)) provides a scalable fabrication procedure, and the use of commercially-available and high tap-density LIB active materials with the lightweight aerogels enables fabrication of composite electrodes with practical active-material loadings and electrode densities. This approach is unique from that of many other 3D electrodes that use hydrothermal, chemical deposition, or co-precipitation methods to fabricate low tap-density nanomaterials tethered to a 3D substrate that often result in low mass loadings or low volumetric energy densities.

Rice paddy fields in the Naboc area, near Monkayo on the island of Mindanao, Philippines, have been irrigated four times a year over the last decade using Naboc River water contaminated with mercury (Hg) by artisanal gold mining in the Diwalwal area. Silt containing up to at least 90 mg Hg/kg (d.w.) has been deposited in rice paddy fields during the 1990s and this has been repeatedly mixed into the rice root zone through ploughing. Hg in the rice paddy field soils averages 24 mg Hg/kg and generally exceeds the UK and Canadian soil quality thresholds for agricultural soils as well as the proposed Dutch Intervention value and the USEPA soil ingestion Soil Screening Level (SSL) for inorganic Hg. Much lower Hg concentrations (0.05-0.99 mg/kg) within the range expected for uncontaminated soils, characterise soils on which corn and bananas are cultivated, largely because these are not irrigated with Hg-contaminated water from the Naboc River. The estimated total weekly MeHg intake for a person living in the Naboc area related to the weekly consumption of 2.1 kg of rice grown on Hg-contaminated soils (15 microg MeHg) in conjunction with 1 kg of fish (220 microg MeHg) and 100 g of mussels (50 microg MeHg) from the Naboc River, would total 285 microg MeHg (equivalent to 4.75 microg/kg bw for a 60 kg adult), which is nearly three times the JECFA PTWI of 1.6 microg/kg bw. This will significantly contribute to the population mercury exposure and might explain why 38% of the local inhabitants were classified as Hg intoxicated during a mercury toxicity assessment [Drasch GS, Böse, O'Reilly S, Beinhoff C, Roider G, Maydl S. The Mt. Diwata study on the Philippines 1999-assessing mercury intoxication of the population by small scale gold mining. Sci Total Environ 2001; 267(1-3): 151-168.].

This study was designed to provide a database of the endogenous metabolites in earthworm extracts of the species, Eisenia veneta and Lumbricus terrestris by high resolution 1H-NMR spectroscopy in view of identifying biomarkers of toxicity or stress in environmental metabolomics studies. 1D and 2D NMR spectroscopic techniques enabled the identification and confirmation of the organic components in the tissue extracts of whole and segmented earthworms, dissected organs, and coelomic fluid. The extracts gave rise to characteristic 1H-NMR spectral fingerprints of the low MW metabolites contained, specific to the species of earthworm, and to the specific regions or dissected organs of the earthworms under investigation. Distinct changes in the normal biochemistry were observed upon starvation and cooling, such as markedly decreased glucose and maltose, but increased lactate, acetate, succinate, formate and acetone. Additionally, slightly decreased threonine, arginine, lysine, leucine, citrate, asparagine and glycine were observed. Furthermore, lactate could be identified as a biomarker of acute toxic stress in expressed coelomic fluid following exposure to a model ecotoxin (3-trifluoromethylaniline). This work supports the application of 1H-NMR spectroscopy for the study of changes in the normal invertebrate biochemistry in order to allow for the reliable assessment of biomarker responses following toxicity testing.

Potential contamination at ex-industrial sites means that, prior to change of use, it will be necessary to quantify the extent of risks to potential receptors. To assess ecological hazards, it is often suggested to use biological assessment to augment chemical analyses. Here we investigate the potential of a commonly recommended bioassay, the earthworm reproduction test, to assess the status of urban contaminated soils. Sample points at all study sites had contaminant concentrations above the Dutch soil criteria Target Values. In some cases, the relevant Intervention Values were exceeded. Earthworm survival at most points was high, but reproduction differed significantly in soil from separate patches on the same site. When the interrelationships between soil parameters and reproduction were studied, it was not possible to create a good model of site soil toxicity based on single or even multiple chemical measurements of the soils. We thus conclude that chemical analysis alone is not sufficient to characterize soil quality and confirms the value of biological assays for risk assessment of potentially contaminated soils.

Heightened concerns regarding the protection of terrestrial ecosystems at a national level has increased the need to develop a suite of indicators capable of assessing the quality, integrity and fertility of soils. Of the assays currently available, tests that measure aspects of soil function and associated parameters are among the most promising, since these integrate effects on soil quality at the highest level of organisation. In this study we describe results of the deployment of an indicator of soil functional integrity (the bait lamina test) that is designed to measure the feeding activity of soil invertebrates. Bait lamina was used at six grassland sites located along a transect from a smelter at Avonmouth (South-West England) used in the EU funded BIOPRINT II project. Results indicated highest bait removal (feeding) at sites furthest from the factory, intermediate feeding activity at intervening sites and extremely low activities at the two sites closest to the smelter. The strong decline in activity for the group of sites closest to the smelter corresponded with increasing metal concentrations suggesting a clear impact of metals on detritivorous invertebrate feeding. Comparisons of the results of the bait lamina study to previous invertebrate survey work suggested that the differences in observed bait removal can be attributed to direct effects of metals on the abundance and biodiversity of key decomposer groups such as earthworms, isopods, molluscs, myriapods, springtails and mites.

Earthworms were taken across an environmental gradient of metal contamination for ecotoxicology assessment. Both indigenous (Lumbricus rubellus and L. terrestris) and introduced earthworms (Eisenia andrei, exposed in mesh bags) were studied. Changes in the levels of small molecule metabolites in earthworm tissue extracts were analysed by 1H NMR spectroscopy as a means of identifying combination biomarker compounds. Principal components analysis of the NMR spectral data revealed that biochemical changes were induced across the metal contamination gradient. Native worms (L. rubellus) from the most polluted sites were associated with an increase in the relative concentration of maltose; a decrease was also seen in the concentration of an as yet unidentified biomarker compound. Introduced worms (E. andrei) did not show differences to the same extent. Direct integration of the resonances from histidine and 1-methylhistidine showed that relative histidine concentrations were elevated slightly for L. rubellus, confirming the results of earlier mesocosm studies. Conversely, the relative concentrations of both histidine and 1-methylhistidine were greatly reduced by metal contamination in L. terrestris. This study demonstrates the utility of NMR spectroscopy in detecting previously unknown potential biomarkers for ecotoxicity testing and identified maltose as a potential biomarker compound deserving of further study.

The synanthropic landhopper Arcitalitrus dorrieni (Hunt) is largely restricted to the south-west of Britain although there are isolated populations outside this area. It has been recorded from 60 new 10-km squares since Harding and Sutton (1988) last reviewed its distribution. Some of the new records, particularly in south Wales, could be interpreted as meaning that there has been range expansion in this time. However, the evidence is equivocal. It was not possible to explain the distribution of A. dorrieni in terms of association with native plant species. The main means of dispersal still seems to be synanthropic. Arcitalitrus dorrieni has retained a mainly coastal distribution, with penetration inland restricted to peninsular areas (with some notable exceptions, e.g. populations in London).

This study correlates sub-organismal changes with toxicological effects in earthworms (Lumbricus rubellus) exposed to copper and cadmium. Both metals reduced survival and reproduction at the highest concentration (LC50 5.11 microM Cu g(-1) and 4.04 microM Cd g(-1); cocoon production EC50s 5.17 microM Cu g(-1) and 1.86 microM Cd g(-1), all values as dry mass soil). Cadmium significantly reduced lysosomal membrane stability (at 1.86 microM Cd g(-1) and higher), upregulated metallothionein gene expression (at least sevenfold in all treatments) and reduced lysosome-associated-glycoprotein gene expression. Copper did not lower lysosomal membrane stability, but did upregulate metallothionein gene expression (at 2.5 microM Cu g(-1)), reduce lysosome-associated-glycoprotein gene expression and gave a nonlinear pattern for mitochondrial ribosomal subunit transcript expression (reduced at 0.35 and 0.811 microM Cu g(-1); higher at 2.5 microM Cu g(-1)). Correlation of metal body residue concentrations and cellular and molecular genetic responses with juvenile production rate confirmed a relationship for metallothionein expression, lysosomal membrane stability and cadmium tissue concentration in cadmium-exposed worms. Relationships between responses were also found for both metals. These suggested mechanisms for the interaction of cadmium and copper with specific gene products and with organelle (mitochondrial, lysosomal) functioning.

A pedological characterisation of seven sites along a transect from a smelter at Avonmouth, UK, was undertaken. Site locations comprised a mixture of both grassland (5 sites) and oak tree dominated (2 sites) areas. Geographically, sites were either low lying or on adjacent elevated ground. Across the transect, a severe gradient of metal concentrations was found with highest values for organic soil horizons from close to the factory. Comparisons with quality standards indicate that these metal levels are likely to be a major ecological stressor. In addition to the strong metal gradient, a number of other between site differences were also observed. These were firstly water regime, which at the low lying sites close to the smelter showed influence by both, groundwater and stagnant water, while at more distant sites indicated susceptibility to stagnant water only, and secondly soil pH, which showed large between site variations, although no consistent trend along the transect. Humus forms at sites more than 1.5 km from the smelter were characteristic for the soil conditions and land-use present, while those at sites within 1.5 kin, showed disturbed profiles. Indeed, the humus types present at these locations suggest that the activity of soil invertebrates may be inhibited. This is almost certainly due primarily to the high concentrations of metals that were present in mineral soil and organic horizons at the sites. However, the potential influences of water regime and pH could also be relevant factors influencing the results of any further studies conducted at these study sites.

The ability of biomarkers to integrate effects of chemicals on biota has lead to increased calls for their application in assessing the status of polluted ecosystems. In tandem there has been an increase in our knowledge of the ecophysiological responses of keystone species to pollutants, which has allowed the development of a number of promising methods. In contrast to the number of biomarker development studies, the number of biomarker validation studies has remained limited. This paper redresses this imbalance by drawing together data from studies that have used the earthworm lysosomal membrane stability response (measured using the neutral red retention assay). This review first gives a short history of the biomarker's development. Second, it sets published applications of the technique against established criteria for a "good" biomarker (i.e., dose-response relationship, sensitivity, ecological relevance, confounding factors, chemical specificity, species differences, time-response relationship, methodological concerns, and overall public/regulator confidence, and acceptance). Discussion of the biomarker's suitability to each criterion is followed by an overall evaluation of its workability for routine soil quality assessment and caveats for its use.

We investigated key physiological tolerances of the invasive euterrestrial talitrid amphipod (or landhopper) Arcitalitrus dorrieni; desiccation, salt, high and low temperatures. The critical relative humidity below which, A. dorrieni experiences desiccation stress is very high (95-100%), making it completely reliant on the leaflitter/soil microhabitat. It is tolerant of a wide range of (sea) salt concentrations (5-750 mOsmol l(-1)) but is extremely vulnerable below 5 mOsmol l(-1). A. dorrieni does not tolerate low temperatures with a mean lower limit of 1.4 degrees C, but with no individual surviving0 degrees C. The range of upper thermal tolerance (30-37.3 degrees C) was similar to that found for other landhopper and beachflea species. Based on its tolerance to these environmental factors it is suggested that A. dorrieni has a limited potential to invade further into Britain, being restricted to areas with sufficiently high ion concentrations and mild winters.

In many cases, the link between industrial emissions and damage to the environment can only be inferred. The Environment Agency of the United Kingdom imposes emissions limits on industrial sites so that predicted concentrations and deposition rates remain below standard thresholds. Estimates of appropriate critical levels and loads are usually based on laboratory results and rarely estimate synergistic effects between pollutants or consider biological adaptation or selection in the target receptor organisms. The Avonmouth smelter has been emitting zinc and other heavy metals since 1929. It has been the subject of a number of detailed and synoptic studies, especially the impact on soil invertebrates. Damage was assessed using both physiological and ecological measurements. Two methods of spatial analysis were investigated, namely interpolation using standard geographical information system (GIS) operators and atmospheric dispersal modeling using an off-the-shelf model. Both methods can be used to compute contours (isolines) of predicted biological effect. Correlation results show that dispersal modeling is at least as good as kriging but requires much less data. This article demonstrates the usefulness of GIS and dispersal models as tools in decision making to determine the most suitable sampling sites in the assessment and monitoring of the impact of contamination around major point sources.

At present there is little knowledge about how density regulates population growth rate and to what extent this is determined by life-history patterns. We compared density dependent population consequences in the Nicholsonian sense based oil experimental observations and life-history modeling for the earthworms Lumbricus terrestris and Eisenia fetida. Both species differ in their life-histories, L. terrestris being a relatively long-lived species with slow reproduction and occurring at low densities compared to E. Jetida which has a more opportunistic strategy with a high reproductive output. E.fetida is able to colonise new habitats rapidly and may occur at relatively high population densities. Density dependency of population growth rate was estimated by incorporating density dependent effects on reproduction and growth using a modified Euler equation. The results point out that E. fetida was not as strongly impacted by density as compared to L. terrestris. Population growth rate in E. fetida was hardly affected at low and moderate density, being reduced only at high level, this compares to L.terrestris where even relatively small density effects resulted in a strong negative effect on population growth rate. Our findings indicate that density-dependent regulation in earthworms can be quantified using life-history analysis. The outcomes are in agreement with empirical field observations for populations (i.e. L. terrestris occurs at low density, E. fetida at high density). Consideration of the potential importance of Nicholsonian density dependence for field populations of these two species in light of their known biology however produces counterintuitive conclusions. In E. fetida, although density tolerant, rapid population growth may mean this species may be subject to density dependent regulation. In L. terrestris, although density sensitive, complex behavioural ecology (surface activity, territoriality) may limit of feedback influence on population size.

Summary The inception, ring-testing and standardisation of the acute earthworm toxicity test (OECD 1984), has been at catalyst for the emergence of earthworms as one of the key organisms in (environmental) toxicology. In recognition of this role, there have now been three International Workshops on Earthworm Ecotoxicology (Sheffield in 1991, Amsterdam in 1997 and Aarhus, in 2001). At each workshop delegates met to outline recent work and identify future priorities. At the end of each workshop, recommendations were drawn up both to act as a summary of current knowledge and as initiators for future research. In this paper we briefly review progress in respect of these recommendations. Overall, advances have been made in many areas. Test procedures for laboratory and field toxicity tests have been improved and diversified, thus allowing specific studies not covered by the original OECD (1984) procedure. Further, there is now improved understanding of factors that can modify the effects of chemicals in dynamic ecosystems and also of the mechanistic basis of toxicosis (although many uncertainties still remain in these areas). One notable area where progress has been slower is development of a linked earthworm ecotoxicology community. In particular recommendations to develop comprehensive databases have yet to be implemented.

High-resolution 1H nuclear magnetic resonance (NMR) spectroscopy can be used to produce a biochemical fingerprint of low-molecular-weight metabolites from complex biological mixtures such as tissue extracts and biofluids. Changes in such fingerprint profiles can be used to characterize the effects of toxic insult in in vivo systems. The technique is nonselective and requires little sample preparation or derivatization. In the present study, earthworms (Eisenia veneta) were exposed to three different model xenobiotics by a standard filter paper contact test, and toxicant-induced biochemical changes were then investigated by characterizing the changes in endogenous metabolites visible in 600-MHz 1H NMR spectra of tissue extracts. The NMR spectral intensities were converted to discrete numerical values and tabulated in order to provide data matrices suitable for multivariate analysis. Principal component analysis showed that changes had occurred in the biochemical profiles relative to the undosed controls. The 2-fluoro-4-methylaniline-treated worms showed a decrease in a resonance from a compound identified as 2-hexyl-5-ethyl-3-furansulfonate using a combination of high-performance liquid chromatography (HPLC)-Fourier transform mass spectrometry (IonSpec, Lake Forest, CA, USA) and 1H and 13C NMR spectroscopy. An increase in inosine monophosphate was also observed. The 4-fluoroaniline-treated worms showed a decrease in maltose concentrations, and 3,5-difluoroaniline exerted the same effect as 2-fluoro-4-methylaniline but to a lesser extent. These changes could potentially be used as novel biomarkers of xenobiotic toxicity and could be used to determine the mechanism of action of other toxic chemicals.

The lysosomal neutral red retention time (NRRT) assay, a biomarker for lysosomal membrane stability, and the total immune activity (TIA) assay, a measure of non-specific immune system activity, were used in laboratory studies to assess the toxic effects of 2,4,6-trinitrotoluene (TNT) on earthworms (Eisenia andrei) in vivo. The results were compared with the concentration of TNT and its metabolites in earthworm tissue, as well as standard sublethal toxicity endpoints including growth (i.e. weight change) and reproduction effects from previously published studies. Filter paper experiments indicated a significant decrease in NRRT at gtoreq1.8 mug TNT cm-2, whereas sublethal (weight loss) and lethal effects to earthworms were detected at gtoreq3.5 and 7.1 mug TNT cm-2, respectively. Experiments in artificial soil showed that NRRT effects could be detected at lower TNT concentrations (gtoreq55 mg TNT kg-1 soil dry weight) compared with other sublethal endpoints (effects on growth and reproduction). The TIA biomarker did not significantly respond to TNT. Cooper (as CuSO4, filter paper contact tests) and 2-chloroacetamide (soil tests), which were used as reference toxicants, also decreased the NRRT. The use of the NRRT assay linked with tissue concentrations of TNT metabolites in earthworms was identified as a potentially appropriate biomarker approach for TNT exposure assessment under laboratory conditions and a novel tool for effects-based risk assessment. (c) Biosciences Information Services.

Eisenia fetida was exposed in the laboratory to a range of elevated soil copper (Cu) concentrations under two different contamination histories. An EC10 for reproduction was observed at 34 mg Cu/kg for soil spiked with Cu 1 d prior to running the experiment (newly spiked soil). Soil contaminated with Cu in the field more than 70 years previously (field-contaminated soil) caused a 10% decrease in reproduction at 248 mg Cu/kg. Survival and cocoon wet weights were not affected by soil concentrations up to 1,400 mg Cu/kg under either contamination history. Adult growth was reduced at 428 mg Cu/kg (EC10) in newly spiked soil but not in field-contaminated soil at concentrations up to 1,400 mg Cu/kg. The contamination history, as well as the toxicological parameter, was important in the interpretation of the outcome of a standard laboratory toxicity test. The lysosomal membrane stability of coelomocytes, measured as neutral-red retention time (NRR-time), was reduced at soil Cu concentrations lower than those affecting reproduction and demonstrated a dose–response relationship. The NRR-time was more severely reduced in worms exposed to newly Cu-spiked soil (EC10 = 8 mg Cu/kg) than worms exposed to field-contaminated soil (EC10 = 69 mg Cu/kg). The NRR-time reflected the bioactive Cu fraction, showing a good correlation with reproduction under both contamination histories.

The collembolan Folsomia fimetaria L. was exposed in the laboratory to a range of elevated soil copper concentrations under two different contamination histories. These results were compared with the in situ abundance of F. fimetaria in a copper-contaminated field site. In the laboratory studies, an EC10 of 337 mg Cu/kg was observed for soil spiked with copper 1 d before the experiment. Using soil from a field site contaminated with copper more than 70 years previously, no effect was observed at concentrations as great as 2911 mg Cu/kg. Reproduction was threefold more sensitive than mortality or growth. Differences in copper sensitivity between sexes and between juvenile clutches were also indicated. The abundance of F. fimetaria showed no change with soil copper concentrations during the first year (spring sampling) of in situ observations. During the second year (autumn sampling), a reduced number per area was observed with increasing soil copper concentrations. Both the presence and abundance of other euedaphic collembolans generally exhibited distribution patterns similar to those of F. fimetaria. Thus, the contamination history and the toxicological endpoint were very important for interpreting the outcome of the standard laboratory toxicity test. Laboratory studies to some extent reflected the in situ abundance, but this depended on the contamination history and the field sampling time. Laboratory experiments using new copper-spiked soil provided the lowest effect levels.

(1)H NMR spectra of earthworms Eisenia veneta treated with 3-trifluoromethyl-aniline in a 72-h contact filter paper test have been analysed using pattern recognition techniques to determine the biochemical response. Various strategies for data reduction of the metabolite profile, and illustration by principal components analysis are applied and discussed. The use of mean principal components plots in simplifying group data representation and highlighting the dose-response function is demonstrated. Hierarchical cluster analysis, and cluster significance analysis of the principal components were also used to examine the relative distribution of dose groups. Identification and assignment of metabolite responses to toxicity were found via correlation coefficient-shift plots. As measured by the correlation coefficients alanine was the most significant metabolite, but increased levels of other amino acids such as glycine and asparagine were also observed. Further, elevated levels of glucose, and the citric acid cycle intermediates citrate and succinate were noted as potential biomarkers of toxicity. This work provides a basis for examining the biochemical response of invertebrates to toxins. This should provide a framework to examine toxicity effects of other halogenated aromatic pollutants to earthworms used as environmental monitors.

To evaluate the impact of land-based contaminants on benthic faunas, as part of the Land-Ocean Contamination Study (LOCS), a study transect was established in Jakarta Bay, Indonesia during the 1996 southeasterly monsoon. The transect extended 72 km between the city's main port, Tanjung Priok, and the Pilau Seribu Island chain in the Java Sea. The dissolved concentrations of Pb, Cu, Zn, Cr and Ni in seawater, in suspended particulate matter (SPM) and surficial sea bed sediments were measured along the transect at nine sites. In addition, metal concentrations were measured in tissues of the corals Goniopora lobata and Lobophyllia hemprichii at five sites, and of the green mussel, Perna viridis at six sites. An assessment of the impact of contaminants on the faunas was made using a biomarker approach, employing coral community analysis and lysosomal stability with Perna viridis. The results of the study showed two main trends. The distributions of metals dissolved in seawater, in SPM, and in the coral and mussel tissues were similar, and failed to show a consistent graded response from inshore to offshore sites. This suggests that the concentration of metals in waters is the primary route for metal uptake by the coral and mussel tissues. By way of contrast, a clear offshore increase in coral generic diversity, coral cover, coral colony numbers and neutral-red retention time (lysosomal stability) was observed, aug gesting increasing nearshore stress. Whilst the coral community stucture may reflect the seasonally-averaged metal distributions in the bay (shown by the metal content of sea bed sediments which increase shorewards), it is more likely that the coral community structure and lysosomal biomarker are responding principally to other nearshore stresses, such as sediment and nutrient loading of water (sewage) or, more likely, organic contaminants such as oils and other hydrocarbons., Dans le cadre du programme Contamination Continent-Océan (LOCS, Land-Ocean Contamination Study), l'impact des contaminants terrestres sur la faune benthique du golfe de Djakarta (Indonésie) a été évalué en 1996, pendant la mousson du sud-est, sur une radiale de 72 km entre le port principal Tanjung Priok et la chaîne insulaire Pulau Seribu, dans la mer de Java. Les concentrations de Pb, Cu, Zn, Cr et Ni dissous ont été mesurées : 1) dans l'eau de mer, dans les particules en suspension et dans les sédiments superficiels (9 stations) ; 2) dans les tissus des coraux Goniopora lobata et Lobophyllia hemprichii (5 stations) ; 3) dans les tissus de la moule verte Perna viridis (6 stations). L'impact des contaminants sur la faune a été évalué à l'aide d'un marqueur biologique, par analyse de la communauté corallienne et stabilité lysosomiale avec Perna viridis. Deux tendances principales ressortent de cette étude. Les répartitions des métaux dissous dans l'eau de mer, dans les particules en suspension et dans les tissus des coraux et des moules sont similaires, sans variation entre la côte et le large, ce qui suggère que l'eau est la voie d'absorption des métaux par les tissus des coraux et des moules. À l'inverse, une nette augmentation est observée au large dans la diversité des genres coralliens, dans la couverture corallienne, dans le nombre des colonies de coraux et dans le temps de rétention du rouge-neutre (stabilité lysosomiale), ce qui indique un accroissement des contraintes vers la côte. Bien que la structure de la communauté corallienne représente la moyenne saisonnière de la répartition des métaux dans le golfe (illustrée par la teneur en métal des sédiments, croissante vers le rivage), il est probable que la structure de la communauté corallienne et le biomarqueur lysosomial répondent surtout à d'autres contraintes côtières, comme la charge en sédiments et en nutriments (égouts) ou, plus probablement, en contaminants organiques tels que le pétrole et les autres hydrocarbures.

High resolution 1 H nuclear magnetic resonance (NMR) spectroscopy has been used to investigate the low molecular weight metabolite composition of the whole haemolymph of 5th instar larvae of the Tobacco Hornworm, Manduca sexta . This technique provides a rapid, multicomponent profile of a wide range of intermediary metabolites. Assignment of the 1 H NMR resonances in the 1-dimensional spectrum has been facilitated by the use of high frequency 2-dimensional NMR techniques, including J-resolved spectroscopy, 1 H– 1 H total correlation spectroscopy and 1 H– 13 C heteronuclear correlation spectroscopy. Amongst the biochemically important metabolic intermediates that were detected in whole haemolymph were trehalose, glucose, alanine, lactate, choline and betaine. In total, it was possible to simultaneously detect and potentially quantify 19 endogenous metabolites. These studies indicate that NMR spectroscopy of the whole larval haemolymph may offer the potential for evaluation of whole organism biochemical status in relation to physiological or environmental stress.

Effects of nanoparticles on aquatic organisms have been little studied to date and toxicological data are urgently needed for development of regulatory frameworks for these substances. Here, we report the findings of a study exposing sticklebacks to cadmium sulfide (CdS) as bulk material and quantum dots. Fish were exposed for 21 d in a flow through test system to 5, 50 or 500 microg l(-1) CdS nanoparticles (nCdS) coated in thiol terminated methyl polyethylene glycol (MPEG), bulk CdS or MPEG at 500 microg l(-1) (nominal concentrations). With the exception of the highest nCdS exposure, measured concentrations were approximately one order of magnitude below nominal. A single fish from each group (excluding MPEG) was examined using energy dispersive X-ray analysis (EDX) to localise cadmium, however, cadmium could not be detected in whole body sections. Elevated levels of oxidized glutathione were measured in the gills of fish exposed to 50 and 500 microg l(-1) nCdS. Induction of vitellogenin synthesis was not detected in any of the treatment groups. The number of males engaged in nest-building behaviour following exposure to 500 microg l(-1) nCdS was reduced and livers of 4/6 fish in the same treatment displayed hepatocellular nuclear pleomorphism. The results are discussed emphasising the fundamental importance of experimental design and the need to understand the behaviour of nanoparticles in the aqueous phase.